| Author | Nguyen, Le Hung |
| Call Number | AIT Thesis no.AE-93-13 |
| Subject(s) | Fruit juices
|
| Note | A thesis submitted in partial fulfillment of the requirements for the Degree of Master of Engineering. |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. AE-93-13 |
| Abstract | In this study the potential of continuous flow heating systems was investigated for pasteurizing fruit juices. Two types of test cells were designed and fabricated for the ohmic heating system, and their performance was evaluated. Tests revealed that a heating cell with rectangular electrodes positioned along the flow perpendicular to applied AC field performed better than the test cell with perforated electrodes placed across the flow. However the test cell configuration led to the higher values of electrical conductivities and thus necessitating the determination of a cell factor. The cell factor varied from 1.07 to 1.24 depending on the liquid height above the electrodes and the material used. Based on energy balance during ohmic heating, a computer model was developed for predicting the change s in current and fluid temperature for fixed applied voltage and flow rate . The model predicted the performanc e of ohmic heating unit both in transient and s teady state operations. Results showed good agreement between the model-predicted and the experimental performance. After initial warming- up of the system in about 300 to 500 seconds, the fluid temperature could be raised from room temperature to pasteurization level in less than 100 seconds using flow rates higher than 160 g/min. Pasteurization of tangerine and pineapple juices with different temperature - time combination in ohmic heating were comparable to conventional water bath method. In addition, ohmic heating effectively destroyed the microorganisms without any changes in physical quality of fruit juices. |
| Year | 1993 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. AE-93-13 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Jindal, Vinod K. |
| Examination Committee(s) | Ilangantileke, Sarath G.;Athapol Noomhorm;Vincent, Jean - Claude |
| Scholarship Donor(s) | The Government of New Zealand. |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1993 |